Spore dispersal in the intertidal kelp Lessonia spicata: macrochallenges for the harvested Lessonia species complex at microscales of space and time

Abstract

Abstract The intertidal coast of Chile has two cryptic kelp species, Lessonia spicata and L. berteroana, which share closely situated, but not overlapping, high-energy habitats. Their populations recover slowly after major disturbances and massive mortalities, suggesting that dispersal from remnant populations is strongly limited. This low dispersal is also a factor that probably favours the speciation process. Understanding the limiting factors for spore dispersal is crucial. Here we evaluated 1. spore dispersal and spore dilution over distance, 2. if submersion in calm waters for a specific period of time is needed for the settlement of spores before exposure to water movement, and 3. duration of spore attachment ability. Results were consistent with the hypothesis of low-distance dispersal of spores: stained-spore dilution was high at short spatial scales (<4 m); spores settled quickly (1–2 min) even under constant water movement, but they lost the ability to attach rapidly (≤16 h). Water motion did not affect spore attachment to the substratum, a fact probably resulting from an adaptation to high energy intertidal habitats. The very low dispersal range of the spores may explain the strong genetic differentiation at small spatial scales, the speciation event that occurred within the Lessonia species complex and the slow recovery of L. berteroana after massive mortalities occurring with the 1982/1983 El Niño Southern oscillation event.